This invention relates to improvements in windmills and more particularly to windmills of the class that include a plurality of vanes rotating in a horizontal plane on a vertical shaft.
The windmill disclosed herein utilizes the well known expedient of vanes that swing closed when in the wind and swing open when coming into the wind and provides certain improvements to increase the efficiency, utility and stability of such devices.
In prior devices of this class, vanes have been made of rigid material such as sheet metal or the like and also of fabric material with both types being securely fixed to a supporting structure in their various positions of operation.
With the above observations in mind, one of the important objects of this invention is to provide a construction for improved operation and utility in a multi-vane windmill of the type rotating in a horizontal plane on a vertical shaft.
Another object of this invention is to provide a windmill structure of the class characterized that includes frame supported vanes which swing closed when in the wind to utilize the wind forces and swing open when coming into the wind to reduce wind resistance and also include means for reducing the wind catching capability of the vane under extreme wind forces and thus automatically prevents excessive speeds and reduces stresses.
More particularly, it is an object of this invention to provide a windmill of the above class which includes fabric vanes within a vertical frame and normally held taut therein by attaching means capable of sliding relative to the frame sides and releasably secured to the top of the frame so that under extreme wind forces, the vanes become disengaged from the top of the frame and collapse toward the bottom thereof to reduce the vane area available for catching the wind.
A further object herein is to provide a second embodiment of vane construction for a windmill as characterized which includes a two piece overlapping vane secured taut within a suitable frame and normally held in overlapped or closed position by yielding means that permit the pieces to separate under high winds to provide an air passageway through the vane and thus reduce speed and stresses.
A still further object herein is to provide an improved stop for limiting the swinging movement of the vane frame to assure effectiveness in efficiently utilizing the wind forces.
The foregoing objects and such further objects as may appear herein, or be hereinafter pointed out, together with the advantages of this invention will be more fully discussed and developed in the more detailed description of the accompanying drawings.